Question

a train crosses a electric pole in 10 seconds and plaform in 15 second .the lenght of the platfoam is 100 meter .what is the speed of train

Answer 1

Let length of train =L
So, time taken crossing poll is the time to travell there length
Time T=distance D/speed S
10=L/S
S=L/10
L=10S
now,
Train crosses 100m plateform in 15 second
Then from formula T=D/S
15=(100+L)/S
S=(100+L)/15---------(2)
put value of S from eq1 in eq2
S=(100+10S)/15
15S-10S=100
5S=100
S=100/5
S=20
hence speed of train S=20meter/sec